Touch systems are well known in the art and typically include a touch screen or panel having a touch or input surface on which contacts are made using a pointer in order to generate user input. Pointer contacts with the touch surface are detected and are used to generate corresponding output depending on areas of the touch surface where the contacts are made. Many types of touch systems exist that utilize different technologies to identify pointer contacts with the touch surface. These technologies include for example analog resistive, electromagnetic, capacitive, acoustic or machine-vision detection arrangements to identify pointer contacts with the touch surface.
For example, International PCT Application No. PCT/CA01/00980 filed on Jul. 5, 2001 and published under No. WO 02/03316 on Jan. 10, 2002, assigned to SMART Technologies Inc., assignee of the subject application, discloses a camera-based touch system comprising a touch screen that defines a touch surface on which a computer-generated image is presented. Depending on the application, a front or rear projection device may be used to project the image that is visible on the touch surface. A rectangular bezel or frame surrounds the touch surface and supports digital cameras at its corners. The digital cameras have overlapping fields of view that encompass and look across the touch surface from different viewpoints. The digital cameras acquire images looking across the touch surface and generate image data. Image data acquired by the digital cameras is processed by digital signal processors to determine if a pointer exists in the captured image data. When it is determined that a pointer exists in the captured image data, the digital signal processors convey pointer characteristic data to a master controller, which in turn processes the pointer characteristic data to determine the location of the pointer in (x,y)-coordinates relative to the touch surface using triangulation. The pointer coordinate data is conveyed to a computer executing one or more applications programs. The computer uses the pointer coordinate data to update the computer-generated image that is presented on the touch surface. Pointer contacts on the touch surface can therefore be recorded as writing or drawing or used to control execution of applications programs executed by the computer.
Interest in machine vision touch systems has increased with the result being a growing demand for such touch systems with larger touch surfaces. In many environments such as in teaching institutions, very large scale touch systems are desired so that visible presentations can be made to large groups. To meet this need, a very large scale touch system has been designed and is described in U.S. patent application Ser. No. 10/750,219 to Hill et al., assigned to SMART Technologies Inc. This very large scale touch system comprises a touch panel having a plurality of input sub-regions that overlap to define a generally contiguous input surface. Each coordinate input sub-region has associated cameras that acquire overlapping images looking across the input sub-region and that generate pointer coordinate data in response to pointer contacts on the input surface. The pointer coordinate data is processed to update image data presented on the input surface. When a pointer contact is made on a portion of a coordinate input sub-region that does not overlap with an adjacent coordinate input sub-region, the coordinate input sub-region processes acquired images to derive pointer data and triangulates the position of the pointer using the derived pointer data thereby to determine the position of the pointer contact relative to the touch surface. When a pointer contact is made on a portion of a coordinate input sub-region that overlaps with an adjacent coordinate input sub-region, each overlapping coordinate input sub-region processes acquired images to derive pointer data and triangulates the position of the pointer using the derived pointer data. The triangulated positions generated by the overlapping coordinate input sub-regions are then processed in accordance with defined logic thereby to determine the position of the pointer contact relative to the touch surface.
In the above-described Hill et al. touch system, as in many touch systems, the touch panel comprises a rigid, one-piece substrate and a low-gloss, dry-erase laminate sheet adhered or otherwise secured to the substrate and defining the input touch surface. As will be appreciated, manufacturing and shipping such a large scale touch panel is expensive. Also, as the demand for even larger touch panels increases, so do the associated manufacturing and shipping costs. As a result, there exists a need for less expensive touch panels.
It is therefore an object of the present invention to provide a novel touch panel and interactive input system incorporating the same.